Display panel or portion thereof with a transitional graphical user interface



FIG. 1 is a front view of a display panel or portion thereof with a transitional graphical user interface, showing a first image in a sequence of a first embodiment of a new design;

FIG. 2 is a second image thereof;

FIG. 3 is a front view of a display panel or portion thereof with a transitional graphical user interface, showing a first image in the sequence of a second embodiment of the new design; and,

FIG. 4 is a second image thereof.

The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1-2 and 3-4. The process or period in which one image transitions to another image forms no part of the claimed design.

The broken lines depicting a display panel or portion thereof are included for the purpose of illustrating portions of the article of manufacture and form no part of the claimed design. 

CLAIM The ornamental design for a display panel or portion thereof with a transitional graphical user interface, as shown and described. 